1. Field of the Invention
This invention relates to methods and apparatus for stripping a protective coating from multi-conductor flat cables. More particularly, the invention is directed to the removing of portions of the protective coating from multi-conductor flat ribbons containing a plurality of optical fibers.
2. DESCRIPTION OF THE PRIOR ART
The present invention is particularly applicable to, and is most readily understood in the context of, stripping flat cables containing glass optical fibers. However, the invention is not so limited, as the instant concepts are applicable to the stripping of any mutli-conductor cable having brittle rods or fibers as the conductor material.
Transmission of information over optical fiber cable is well known. Additionally, it is known that such cables may be formed in a planar array wherein a plurality of parallel optical fibers are encapsulated or bonded within a protective coating in a planar multi-conductor ribbon. Such a planar array appears to be one of the more efficient ways of arranging such ribbons. However, problems arise when the ribbons are to be spliced to another ribbon or terminated at a connector.
In order to terminate or splice such ribbons by butt joining the ends of the glass optical fibers, it is critical that the fiber ends be optically smooth and perpendicular to the axes of the fibers. A method of breaking optical fibers so as to produce such ends is described in an article in the Bell System Technical Journal, entitled, "Optical Fiber End Preparation for Low-Loss Splices," by D. C. Gloge et al., Vol. 52, No. 9, November 1973. This method requires that the fiber be simultaneously bent and put under longitudinal tension, then scored by a sharp blade which causes the fiber to break, or fracture, in a plane perpendicular to the longitudinal axis of the fiber with a smooth, flat surface.
To implement the foregoing fiber breaking method, a section of the protective coating about the fiber was manually removed using a hand-held razor blade or knife. Care had to be taken not to nick or scratch the optical fiber while being careful that a sufficient length of the fiber was exposed for the subsequent scoring step. Once the protective coating was removed, the exposed portion of the fiber was placed over a form having an optimum radius of curvature to ensure the desired cracking. Portions of the fiber on each side of the stripped section were then clamped and a longitudinal force applied to place the fiber in tension as a diamond needle point scored the fiber causing the desired breaking.
Such a procedure incorporating the separate sequential steps of removing the protective coating and then bending the optical fiber prior to scoring and breaking is cumbersome and inefficient.